Coral comeback? New discovery gives hope for reefs and marine life

By Isobel Williams via SWNS

Some coral species are more resilient to climate change than previously thought - as they have learned to survive heat, reveals new research.

Scientists have discovered that some coral species can be resilient to marine heat waves by remembering how they lived through previous ones.

These findings are very important as coral reefs are in decline from a range of human pressures including climate change.

Coral reefs are found in less than one percent of the ocean but are home to nearly one-quarter of all known marine species.

They also help regulate the sea’s carbon dioxide levels and are a crucial source for scientists searching for new medicines.

Lead author and graduate student Alex Vompe said: “Heatwaves are likely to increase in frequency and severity because of climate change.

“Slowing down the rate of coral cover and species loss is a major conservation goal, and predicting and engineering heat tolerance are two important tools.

“It is vital to understand how quickly reefs can adapt to ever more frequent, repeated disturbances such as marine heatwaves.

“The microbiomes living within their coral hosts might be a key component of rapid adaptation.”

Coral microbiomes are the name given to the community of bacteria and archaea living within corals.

Vompe added: “Climate change is threatening coral reefs in part because some of the relationships between coral and their microbes can be stressed by warming oceans to the point of dissolution.

“But Acropora retusa, a prevalent coral species in the Mo’orean coral reef that we studied, appears to have a powerful ecological memory response to heat waves that the microbiome seems to play a role in.

“This means some coral species may be more resilient to climate change than previously thought.”

To get their results the team, from Oregon State University, spent five years studying 200 coral colonies at a reef on the north shore of Mo’orea, French Polynesia.

In 2010 more than 99 percent of the corals here were destroyed, effectively hitting the reset button on the reef.

Corals reestablished and went through comparatively minor heat wave events in 2016 and 2017 before experiencing the area’s most severe marine heat wave in recorded history between December 2018 and July 2019.

The second-most severe heat wave soon followed, between February and July of 2020.

This recent history made the reef a uniquely perfect specimen for this study.

The results, published in Global Change Biology, showed that the coral seemed to remember the previous heatwaves and have adapted to survive them.

Professor Rebecca Vega Thurber said: “We observed that some species of coral seem to remember exposure to past marine heat waves and maintain a higher level of health in subsequent heat waves.

“And Acropora retusa’s memory response was strongly linked to changes in its microbiome, supporting the idea that the microbial community has a part in this process.

“In two of the three coral species we focused on, we identified initial microbiome resilience, host and microbiome acclimatization, or developed microbiome resistance to repeated heat stress.

“The latter two patterns are consistent with the concept of ecological memory.”